
"The game does not force players to power their cities any specific way, but allows them to make choices, each of which come with advantages and disadvantages. Similar to real-life, the least expensive and most readily-available buildings in SimCity Societies are also the biggest producers of carbon dioxide, an invisible gas that contributes to global warming. Should players choose to build cities dependent on these types of sources for power to conserve their in-game money, their carbon ratings will rise and, at reaching critical levels, the game will issue alerts about the threat of the various natural disasters like droughts, heat waves and others that may strike their cities."
Wonderland (via Boing Boing)